Does this stuff go bad?I have a 72 with low original miles.I've neglected it to storage for about 3 years and am having some issues.Atm i'm looking at brakes.Pedal seems to go almost to floor.Very weak.I found low fluid in back master cylinder resevoir and topped it up.Didn't really help.I've watched floor and have no leaks and still full.
When i addded fluid,i noticed the fluid was really cloudy.I know the brakes have only been changed 2 times since the car was new and all pads and rotors look like new.

 

Both the fluid and the seals in the system can go bad, particularly if the car is not driven for a while in a humid environment. Moisture can seep in and that tends to do bad things, including making some types of fluid milky.

At the very least you should flush the system well and replace the fluid. This may not fix the problem. I have seen cars that sat for a while with a bit of moisure in the brake fluid develop rust on their caliper pistons and the cylinders of the brakes, etc.

 

If the pedal goe's to the floor and you have no leaks then there's either lots of air in the system or the master cylinder is trash. From your description it sounds like the master cylinder.

 

I agree with air in the lines. And I think it was probably parked like that.

If you got no leaks after three years, and it was not that way when you parked it (strange), do a flush.

Or at least what I do - an end flush... Run a couple of ounces out of the farthest wheel, then the next farthest, second, then the closest.

That's strange that a static hydrophobic(non-moving, anti-water)system would change in three years, since it's low mileage. Usually, you have good integrity of the wheel cylinder rubberout back, and caliper piston rubberup front, and no atmoshphere swappin' to get moistrure in...

If it's low mileage at 35 y/o, it has been idle a few times, and when you punch up the brakes after idle, the rubber ain't gonna' go right through a dry cylinder real good. You then will get air.